The present invention concerns a retinal projection device comprising a movable light source controlled for projecting an image directly onto the retina of a user wearing the device.
Sport activities such as jogging, biking, diving etc. are often practised with a device that display sport related data, such as heart pulse, speed, pace, calories burnt, and so on. Classical data display for sportsman are often based on a wristwatch or on a display mounted on the handlebar of a bike for example. Therefore, the sportsman who wants to read data on the display is distracted from his sport activity, which might be impossible or dangerous depending on the activity.
As a more convenient alternative, it has already been suggested to display sport-related data with a head-mounted display or, more conveniently, with glasses. In one example, sport data are displayed during the sport activity with a retinal projection device.
Retinal projection devices are known as such. They usually comprise a light source and a mems-based mirror arranged for orienting the laser beam directly onto a selected portion of the retina of the user wearing the device. By scanning the laser beam and controlling its intensity, the device projects an image that is superimposed over the image of the scene viewed by the user.
Conventional retinal displays are usually conceived so as to replace a large portion of user's field of view by a projected image. In this case, the user does not see the scene behind the projected area, which is unacceptable for many sport applications where the sportsman needs an unobstructed field of view.
Retinal displays that display a large transparent image overlaid over the real scene are also known. In this case, the user is able to see simultaneously the scene of the real word with an image or some objects superimposed over this view. This is also very distracting for most sport activities where the sportsman needs to concentrate most of the time exclusively on the real scene, and only occasionally wants to see data related to his sport activity.
Displaying a large image with a retinal display requires fast moving mirrors and fast transmission rates for transmitting large image frames. This results in a high power consumption, and in voluminous batteries that frequently needs to be replaced or recharged.
Most retinal display systems moreover require dedicated glasses. Those glasses are usually not well suited for sport activities. Different sports require different type of glasses. For example, large glosses with optimal sun and fog protection are often used for skiing, while jogging is preferably made with lighter sun glasses. Users who need medical glasses have difficulties in using conventional retinal display systems.